Adjust powder or coal?

[Metal god]

I have shot tighter groups before but no consistency with my replica loads. One thing I know could be a factor is all my different casings. (Headstamps)

Oh yes if you want real accuracy you will need to separate your brass by head stamp . No if ands or buts about it . There can be significant case volume differences from one brand to the next . Winchester for example will likely have more case volume then LC . That alone will change your pressure and barrel time and where the bullet leaves the barrel in relation to barrel whip . Once they're separated and you find that great load . Continue to use that brass for that load . You may find another head stamp shoots that load good as well . If so cool for you . How ever I promise you they all will not shoot that load the same .

Next time out separate your already loaded rounds by head stamp and shoot those in groups of 5 . You'll be amazed what you see . I bet you not only see some brass group better then others . You will see POI ( point of impact ) shifts from group to group . Maybe not all but at least one will group in a different place on the target . It wont likely be a huge shift but assuming you can shoot well . It should be noticeable .

METAL GOD that was a hell of a lot of info. Not sure I should start with max oal but will definitely start pushing it towards the lands and see. I know last year I loaded some 168 grn a max with 43 grns 4064 and at .005 off the lands I was blowing an occasional primer out of the case. I think I will play it safe and

That was my very point . As I explained in one of my post

The issue turned out that at 2.845 I get sticky bolts every once and a while that I do not get at 2.815 .

Meaning my 43gr charge at 2.815 was fine with no pressure signs but when I seated the bullet .030 closer to the lands I got sticky bolt lifts ( a clear over pressure sign ) So just seating the bullet closer to the lands with an existing load that had no pressure signs . Suddenly created pressure issues . That IMHO was do to the fact 43gr at 2.815 was already pushing close to max pressures . When I seated the bullets closer to the lands .It created more pressure resulting in sticky/heavy bolt lifts .

In short , yes you are correct in saying I'll play it safe and work my load up .

Here's a load work up a did a little while back

One might ask why do those minimum charges only have 2rds and the complete work up progresses with more and more rounds as the charge weight goes up .

I do that when I have a specific goal in mind . In this case I wanted this load to be a long range 800yd load . So I knew the lower charge weights were not likely to give me the velocities I would be looking for . How ever you should still start at or very close to minimum charge just to be sure you're not over pressure right from the get go . So those lesser charges are there only to be sure I'm safe pressure wise and can continue to the higher charges where I knew my likely final charge would be . At the time I had never used RL-15 or that bullet so I had no idea how my rifle would react to that combo so I made sure I erred on the side of caution and started low .

 

[berettaprofessor]

Thanks for the explanation Metal God. I primarily load pistol and your description makes perfect sense, eps regarding case volumn and burn rates.

 

[taylorce1]

Here is how I load to find accuracy and it has cut down on a lot of shooting to find an accurate load.

1. I find the lands I use a Hornady modified cartridge if I have it, but the old sharpie on the bullet works just fine. I then measure the cartridge using a bullet comparator to find my case length from the bullet ogive. However if the lands are beyond magazine length, I start with magazine length as max COAL.

2. Brass prep sort by head stamp, full length resize, trim to length, chamfer/deburr case mouth, and deburr flash holes. That's it for case prep I'm not bench rest shooting so this is enough for my purposes.

3. Find pressure! I then load up a few (4-5 total) rounds at either .010" back from the lands or at mag length, working my way up to max book load (or slightly over). I observe for pressure signs as I shoot one round always over a chronograph, working my way up to max book load. Once I find a maximum safe pressure in my rifle that is usually what my powder charge is.

4. Run seating depth test according to Berger, I find this test works well with any bullet type not just VLD bullets. I use the test for hunting rifles only again shooting over a chronograph.

Getting the Best Precision and Accuracy from VLD bullets in Your Rifle
Load 24 rounds at the following COAL if you are a target competition shooter who does not worry about jamming a bullet:
1. .010 into (touching) the lands (jam) 6 rounds
2. .040 off the lands (jump) 6 rounds
3. .080 off the lands (jump) 6 rounds
4. .120 off the lands (jump) 6 rounds

Load 24 rounds at the following COAL if you are a hunter (pulling a bullet out of the case with your rifling while in the field can be a hunt ending event which must be avoided) or a competition shooter who worries about pulling a bullet during a match:
1. .010 off the lands (jump) 6 rounds
2. .050 off the lands (jump) 6 rounds
3. .090 off the lands (jump) 6 rounds
4. .130 off the lands (jump) 6 rounds
Shoot 2 (separate) 3 shot groups in fair conditions to see how they group. The remarkable reality of this test is that one of these 4 COALs will outperform the other three by a considerable margin. Once you know which one of these 4 COAL shoots best then you can tweak the COAL +/- .002 or .005. Taking the time to set this test up will pay off when you find that your rifle is capable of shooting the VLD bullets very well (even at 100 yards).

Regards,
Eric Stecker
Master Bulletsmith

Here is how the last time I ran this test with Sierra DTAC bullets worked for me.

5. Load up more and confirm at the range. I always shoot over a chronograph doing this as well until I get a good 10-20 rounds over it. This gives me a great baseline speed to work up my drop charts.

 

[Unclenick]

To support what MG said, here's a plot from Dr. Lloyd Brownell's study of pressures by strain gauge measurement in the mid 1960's, with the pressure data adjusted by a correction factor suggested by Harold Vaughn.

Note that the bullet was a round nose bullet. Such bullets have a very gradual ogive taper between the ogive shoulder where it meets the cylindrical bearing surface, and the point on the ogive where the spherical tip shape commences. That gradual taper means the bullet has to be seated pretty deeply for the annular gap between it and the throat to allow much gas bypass. That's why you see it go so far into the case before the pressure is minimized. With a Spitzer nose the ogive radius decreases diameter much more quickly and opens the annular gap more quickly than the round nose taper shape does. So a much shorter change affects pressure more. The image below shows about 20% pressure decrease just moving 0.030" off the lands with such a bullet.

So, as MG said, if you develop the load with the bullet touching the lands, you will reach pressure at something like a starting load or a little higher, and be perfectly safe seating deeper. How much difference is required is dependent on the powder.

Take a look at Hodgdon's data for 4895 and 4064 with the Sierra 168 grain bullet (not the Barnes 168 grain bullet, which uses less powder). The have:

IMR 4895 Start 41.0 grs, Max 43.5 grs. Pressure change from start to max 129%

IMR 4064 Start 41.5 gr, Max 45.9 grs. Pressure change from start to max 134%.

Note that the pressure changes from start to max are both in the ballpark of 130%. Note that it takes 4064 a 10% change in load to get there, but 4895 needs only a 6% change to get there. 4064 is well known not to increase pressure as quickly with charge weight as 4895. Its burn rate doesn't change with pressure as much as 4895's does in the pressure range of a typical high power rifle cartridge. This grants it some addition immunity to temperature and other factors that affect pressure. Varget is another one like that in 308. They are good for this kind of load workup because their pressures won't increase as much with land contact as 4895 or some other powders whose burn rate is affected more by pressure will.

Take a look at Berger's information on this subject.

 

[cw308]

towman32
The brass your using is fine, as others have mentioned, don't mix your brass. I weigh my sized & trimmed brass try to use the brass within 1 grain of the same weight. Some brass is thicker, that effects volume. Full sizing is fine when you don't oversize. Your case gage is a measuring tool , use your caliper to measure the gage without a case installed. Should measure chamber spec. 1.630 for 308 cal. With your fired case , will to fit in the gage? Then size to bump the shoulder .002 flush with the gage is 1.630. You could have a long chamber, see if a case that is above the gage will chamber.

 

[T. O'Heir]

42 grains of 4064 is just a tick over minimum for a 168. Max OAL is 2.810" for .308. 2.800" is good though. Regardless of what rifle.
Anyway, forget the off the lands stuff until you have a load. It's a load tweaking thing that is different for every rifle and is found by trial and error.
.020" might be good or it might be too much or too little.
Once you have started at the Start load and gone up to the max by half grain increases, you can go back to one load less than the most accurate load and go up by tenths. As in 41.5 to 42.0 by .1 grain.
However, with a Savage M10, it being a hunting rifle, it's probable not worth the time and effort. An inch group is friggin' fantastic. Mind you, it most likely will not do that with a hunting bullet. A-Maxes are not suitable for hunting anything but varmints.

 

[cw308]

towman32
BE ON THE SAFE SIDE. Brass that is thicker ( heavier ) reduce your listed book load by 1 grain. If your charge is 42.0 that is the medium load for IMR 4064 with a 168 grain bullet. With Federal brass being thicker that's 43.0 grains.keep that in mind when loading hot. If your loading for accuracy, medium to low range on your powder. My accuracy load with 4064 is 40.5 in the summer & 41.5 in the colder months 60 - 50 lower then 50 is to cold for my bones.

 

[Rich Coyle]

As soon as I had a maximum load established I would then look for the preferred over all length by loading five of various length. At this point I would not change anything except primers. I would load five with every primer I have and check which one the rifle preferred.

 

[towman32]

That's alot to take in. Thanks everyone. To answer cw308, a case that does not fit flush in my case guage will not chamber in my rifle. As to t.oheir, it's not a hunting rifle, look it up and see, no one would want to pack this heavy thing around the woods! Especially with such a thick barrel. So I'm gonna take a stab at this based on what I've gathered

#1 find identical head stamped brass, pick cases that are within 1 grain of each other. Trim to 2.005, chamfer, debur,swage etc.

#2 take oal measurements with my comparator caliper tool from hornady.(I've done this 5 times with same bullet and got several different readings. As much as .005 diference)do I take the average?

#3 using the 168 a max I start my first 6 rounds with 40.5 grns of 4064 and set bullet .005 off the lands?

#4 once I have found the most accurate load using .3 grn adjustments keeping below max load data, I start the procedure like taylorce1 reccomends to tighten further.

How's this sound?

 

[towman32]

One other thing I wanted to mention, I have several other bullets (nosler, match kings, berger and hornady eldx). I chose the amax to start with just because I have more of them.

 

[cw308]

towman32
Sounds good to me. A - Max is a good bullet, for me I found they shoot better jumped, seating the bullet deeper with less of a charge. Could start with jumping & work up to a jam. To get to your perfect headspace for your chamber, back off your sizing die, lower your die down with each size until your fired case will chamber with a slight resistance that would be your zero headspace. Take that measurement then lower your die to bump the shoulder .002 .

 

[taylorce1]

I'll try to answer your steps in order.

1. IMO unless you're into serious competition shooting there is no need to weight sort your brass. Just sort by head stamps.

2. I'd use the average. Do you use Sharpie on the bullet, or are you using a modified case to find the lands? I have more accurate measurements now that I went to a modified case for my measurements.

3. It doesn't matter what bullet you use, just make sure you start over the whole process when you change bullets. Bullets by different manufacturers all have different shapes, and you can cause pressure spikes by simply changing the bullet you are using.

3&4. Load 1 round each from your starting load up to max book in your .3 grain increments. Don't start looking for accuracy yet, save the bullets for later. If you find pressure back your charge down to the previous charge that had no pressure signs.

5. Once you've established a safe operating pressure then run a seating depth test. This is where you'll find your accuracy, and you'll save a lot of time and components by seeking accuracy as the last step in the process.

 

[cw308]

taylorce1
Weighing & sorting is important for safe and accurate reloads. Every round should be close to exact as possible.

 

[taylorce1]

taylorce1
Weighing & sorting is important for safe and accurate reloads. Every round should be close to exact as possible.

I seriously doubt any ammuniton manufacturer like Hornady, Lapua, Federal, or ect. that make match ammunition weight sort their brass before it goes down the assembly line. My point is depending on what exactly you want to do with the rifle as far as accuracy goes, you can both be accurate and more importantly safe without going to extremes. I know not everyone is going to agree with me, but I don't expect everyone to either.

My process is simple, "accurate, and safe" for my purposes. I'm not saying the OP needs to follow my way, just that I use what works for me. Then there is the fact that I don't have a rifle built nor do I feel that I shoot well enough yet that weight sorting brass is going to offer me any advantages. Plus it just sucks up time reloading that I could spend shooting to get good enough that it might become advantageous.

So I guess we'll just agree to disagree.

 

[cw308]

taylorce1
I understand what your saying . I get my brass from a shooting buddy that doesn't want to reload. His brass is Hornady Match A - Max. 168 gr. 308 cal. I F/L saze only to .0015 case headspace. Every box of 20 I get from him , I size, trim , chamfer inside & out , uniform the primer pockets & flash hole. Then weigh the 20 cases. On every box of 20 I find 1 to 3 cases 3.0+ grains higher in weight, that could explain that one flyer that occurs screwing up your group. I sh*t can those cases. When I mess up a group, I have less excuses to blame it on. Also I'm not reloading large quantities , 30 rounds is a range day, I maybe going overboard on my case peeping 30 cases doesn't take that much time & I like reloading as much as shooting, so the time spent is enjoyable to me. If it were 100 maybe it wouldn't.

 

[Metal god]

CW , I recently started testing case volume with H2o . The fact I've not been doing it for long means I don't have a lot of data on this but my recollection is that 3-ish grain difference in 308 case weight only translates to a few tenths of a grain difference at most in case volume .

I remember comparing Winchester brass to LC . Win was in the high 160's and LC was in the mid 180's so lets say 18gr of weight difference between the two . How ever the case volume difference was only 3gr-ish more like 2.5gr . Keep in mind this is just a general remembrance and although those may not be the exact numbers they are close and reasonably represent my point .

2.5gr is a lot of case volume difference but it took 18gr of case weight to get there . So what I do if I weigh my cases is keep in inside of 5gr . Meaning a +/- of 2gr .

If I remember you are a bench rest guy and "F" class shooter . I can see why you would want to reduce all the variables as small as possible . For me and my type of shooting ( front and rear bag or prone with bi-pod and rear bag ) that +/- 2gr has worked just fine for me . I suspect it would do the same for the OP with where he's at in the grand scheme of things .

 

[cw308]

Metal god
As always, enjoy reading your posts & test results. I have a lot of 1 time fired brass from guy's I shoot with . Rem. Win. FC, HSM, & ADI. I can come up with 30 cases close to the same weight. I'm going to test 6 different brands, with the same case weight, to see if it makes a difference in group size. I shoot rear bunny ear bag & bi - pod set up. As long as the rifle is horizontal with the target, there's no hop.

 

[ka9fax]

e

Originally Posted by T. O'Heir. Once you have started at the Start load and gon up to the max by half grain increases, you can go back to one load less than the most accurate load and go up by tenths. As in 41.5 to 42.0 by .1 grain.

Wow what a great Thread. Alot of good info that i have been looking for. So here is what i have. RL15, 175SMK, The 40g looks to be best, so would i back down to 39.6, 39.7, 39.8, 39.9, 5 of each and look for improvement? the pic's of my groups are 3 shot each, from now on i will make it 5 each

 

[taylorce1]

Wow what a great Thread. Alot of good info that i have been looking for. So here is what i have. RL15, 175SMK, The 40g looks to be best, so would i back down to 39.6, 39.7, 39.8, 39.9, 5 of each and look for improvement? the pic's of my groups are 3 shot each, from now on i will make it 5 each

How far are you loading off the lands? I'd start with your 43 grain load if it shows no pressure signs, and run a seating depth test. More than likely you can dial in the group by simply tweaking the seating depth. Regardless of the powder charge you choose run a seating depth test.

 

[Metal god]

ka9fax ,

I'll start with saying 5 shot groups should be the minimum , That said looking at your groups and applying the OCW method/theory of groping compared with POA to POI . I see two different possible nodes . 39.5 and 40gr are pretty much in the exact same spot on the target so that could be a nice light easy on brass plinking load . 41 through 42 seem pretty close as well as the same POI if you were to triangulate the groups . I also agree that you could probably tweak the 43gr load to tighten up the group .

That all said , the fact it seems a few of the charges would work would indicate to me that you need more shots per group to weed out some of those charges . Shooting at a greater distance would help define them as well .